Entropy provides an unexpected shield in photosynthesis.

Vascular plants combat the excess photon bombarding of high-light conditions with several protective mechanisms. Despite decades of extensive research, new regulatory mech-anisms for photoprotection may remain unknown. Kim et al now report that the monomeric disordered form of photosystem II (PSII), which is present in higher abundance in the native thylakoid membrane in response to high light, possesses an energy-quenching capability superior to that of the multimeric ordered phase, suggesting a new shielding strategy against high-light stress by altering the macro-organization of PSII supercomplexes.